Hundreds of fish die in American Falls Reservoir, A look what caused it

AMERICAN FALLS, Idaho (KIFI) - Hundreds of dead fish were found in American Falls Reservoir. About 250 dead rainbow trout could be seen from the shoreline. Idaho Fish and Game said it was caused by the wind.

Large bodies of water, like the reservoir, have layers of different temperatures from top to bottom. The warmer water at the top has more dissolved oxygen for the fish to breathe.

"So that bottom layer of American Falls Reservoir is typically cold, with very little dissolved oxygen," said Idaho Fish and Game Southeast Regional Communications Manager, Jennifer Jackson.

When high winds come through the area like we had recently--some as strong as 50 to 60 miles per hour.

"Those wind gusts act like a giant spoon, and it literally goes in and churns or turns [the water] over. It mixes that water," Jackson said.

That mixing brings the colder water with much less dissolved oxygen from the bottom to the top.

"So those fish that have been enjoying that sweet spot of perfect temperatures and just the right amount of dissolved oxygen are now hit with the blast of water that has very little dissolved oxygen, and that's enough to cause stress and cause deaths of fish, especially trout, which are particularly sensitive to low dissolved oxygen levels," Jackson said.

She said this happens occasionally. Even though a few hundred fish died, thousands more are left in the reservoir.